Abstract
The role of the electronic state of Pt and acidic properties of anion-promoted support in n-alkane isomerization on Pt-containing sulfate- and tungstate-promoted zirconia (Pt/SZR and Pt/WZR) was studied. The addition of Pt with further oxidation and mild reduction is found to enhance the catalytic activity in n-hexane isomerization 10 times compared with metal-free system. The mechanism of the action of the pretreatment steps is proposed. Effect of the calcination temperature on the catalytic activity in n-alkane isomerization and physico-chemical properties of the catalysts is also evaluated. The catalytic activity of Pt promoted combined sulfated–tungstated zirconia (Pt/SWZR) catalysts in n-hexane and n-pentane isomerization decreases in the following order (the calcination temperature is shown in parentheses): Pt/ SZR (625 ° C)> Pt/ WSZR (625 ° C)> Pt/ WSZR (800 ° C)≈ Pt/ WZR (800 ° C) The properties of WZR (800 °C) and SWZR (800 °C) are connected with the surface WO 4 groups. The presence of sulfate species in Pt/SZR (625 °C) and Pt/WSZR (625 °C) is responsible for the strong acidic properties of these catalysts. The performance of classical sulfated and tungstated catalysts is slightly improved by the combination of anions.
Published Version
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